Multi-purpose stage for electronic probe microanalysis



y 1965 J. LEMAITRE 3,185,84@

MULTI-PURPOSE STAGE FOR ELECTRONIC PROBE MICROANALYSIS Filed May 9, 19 63 s Sheets-Sheet, 1

JNVETUR Jkcyaes LEE .1. LEMAITRE 3,185,840 PURPOSE STAGE FOR ELECTRONIC PROBE MICROANALYSIS May 25, 1965 MULTI 5 Sheets-Sheet 2 Filed May 9, 1963 ATTORNEYS May 25, 1965 MULTI J. LEMAITRE 3,185,849 -PURPOSE STAGE FOR ELECTRONIC PROBE MICROANALYSIS Filed May 9, 1965 3 Sheets-Sheet 3 INVENTOR BY W ATTORNEYS United States Patent 3,185,840 MULTI-PURPOSE STAGE FGR ELECTRONIQ PROBE MICROANALYSIS Jacques Lemaitre, Via per Besozzo 25, Cocquio S. Andrea, Varese, Italy Filed May 9, 1963, Ser. No. 279,144 4 Claims. (Cl. fill-4&5)

This invention relates to an accessory for an electronic probe microanalyser, namely a stage which obviates the need for separate sample and control holders hitherto conventional in this analysis technique.

A stage which already widely satisfied requirements in this respect is disclosed in Belgian Patent No. 608,681. The system is characterized by the combination of a frame comprising a slide guide and a stop for accurate mechanical positioning of the assembly, a dielectric layer, and a metal plate bearing an electron trap, boxes adapted to receive solid samples or controls, and a plurality of sample holder sub-assemblies for thin sections.

The physical feature of this system is therefore the threefold nature of the complete supporting element, while the characteristic application is the analysis of thin sections. It is the particular object of the invention to satisfy practical requirements in respect of these two characteristics, namely the possibility of having available multiple combinations for securing either thin sections or thick test-pieces on a single stage. Another important point for the efiiciency of a microanalyser is the analysis field. The invention provides a considerable advance in this respect as well.

The new stage is characterized in that it forms a frame with a slide guide-known per se-whose part between the base slide guides is formed with series of vertical apertures intended for various purposes (securing of samples, seating, passage), the positions of the apertures agreeing with the test-piece assemblies, and that it has an operating slide guide situated perpendicularly to the base slide guide and being engaged with an operating rod for longitudinal displacement of the stage. The apertures on the central axis of the frame are used to fix the thin section holders or leave a free passage for focussing of the electron beam towards the bottom fluorescent screen of the microprobe (Castaing probe), or for its measurement in the Faraday cylinder. The apertures adjacent this axis are used to hold the securing elements for thick samples and spring leaves for these parts.

The thin section supports are characterized by a screw tube, on the top ring of which are stacked a first support diaphragm, the thin section to be radiographed, a spacer ring, a second support diaphragm, an anticathode thin section and a flared anticathode clamp.

The securing elements are characterized by a leg forming a tubular strut and a conical washer mounted on the leg, whose bottom plane surface is intended to bear against the top surface of the solid samples.

Additional details will be apparent from the accompanying drawing in which one embodiment of the invention is shown by way of non-limitative example and therein:

FIG. 1 is a perspective view of the stage carrying thick pellets clamped by conical washers;

FIG. 2 is a longitudinal section through the stage provided with mushroom-shaped securing elements;

FIG. 3 is a plan view of the stage according to FIG. 2;

FIG. 3a shows the distribution of the securing apertures over the stage;

FIG. 4 is a cross-section on the line lVlV of the stage in FIG. 2;

FIG. 5 is a cross-section through a stage similar to attests Patented May 25, 1965 that shown in FIGS. 1 and 2 but provided with thin section supports, and

FIGS. 6a to 6e show different positions of the samples on the stage.

With reference to FIGS. 1 to 3 and 3a, the new stage is characterized in that it forms a slide-guide frame 10 known per se, whose part 10b disposed between the base slide-guides ltla is formed with series of vertical apertures-see the points of intersection 11a, 11b in FIG. 3 and the apertures themselves in FIG. 3awhich are used for securing purposes, as seatings, and passages as mentioned hereinbefore. The positions of the apertures agree with the assemblies most frequently used for the test-pieces.

The axial distances between the (tapped) apertures 11a are 7 mm., and between the apertures 11!; they are also 7 mm. The lateral distance between the apertures 11a is 15 mm. for the inner lines and 19 mm. for the outer lines. The diameter of the tapped apertures is 6 mm., that of the apertures 11b about 2 mm.

The new stage is also characterized by the operating slide guide 12 mounted on the frame it) perpendicularly to the base slide guides, see the screw 12a. The operating slide guide is rigidly connectedto an operating rod 15 which permits longitudinal displacement of the stage without interrupting the vacuum in the apparatus.

As shown in greater detail in FIG. 2, the rod enters the operating slide 12 by its leg 15a. A knurled ring 16 is secured by a grub screw 17 to the other end. The rod will lock and may be unlocked in any position of the stage system. It replaces the film holder for Kossel lines in the microprobe. On the outside it slides in a transparent tube graduated for locating the various positions of the sample holders on the longitudinal displacement axis and for the successive centring of the thin section supports for their microradiography.

In FIGS. 3 and 3a, the apertures 11b on the two sides of the central axis are usedas already stated herein before-to hold the securing elements for thick samples and spring leaves for these elements. The complete securing element has been given the general reference 13 in the drawing. The apertures 11a on the central axis are intended, as shown in FIG. 5, for securing thin section supports 14 where applicable.

The embodiment of the stage shown in FIG. 1 therefore represents the case of a standardised sample holder for thick pellets (diameter 25.4 mm., thickness 8 mm.). The pellet 23 is the sample to be examined and the pellet 24- is the control. The spring leaves 22 are fixed on the frame 10 to apply the pellets against the securing elements 13.

The struts 24), which are all strictly of the same height, are secured by screws 21 passing through small apertures in the frame in the required position. Conical washers are applied by their bottom plane surface against the top surface of the pellets. All these surfaces are in the same plane, which coincides with the probe focussing plane. The conicity of the washers is such that the latter do not obstruct the passage of the X-rays towards the spectrometers.

Complete freedom is permitted in the choice of location of the struts and the spring leaves as a result of the large number of apertures formed according to the invention in the frame 10.

The application of the new stage to thin section analysis makes it necessary to provide section supports 14 as shown in FIG. 5. They comprise tubes 25 permitting the passage of X-ray or electron beams to the camera disposed therebeneath, and they are screwed in the corresponding axial apertures 11 in the frame 10.

On the top ring of these tubes are stacked a first preparation support diaphragm, then the thin section to be radiog-naphed, then the spacer ring 26 whose thickness depends on the direct magnification to be obtained by projection, and then a.=seco-nd support diaphragm, and tfinally an antioathode thin section and the antioathode clamp 27 which is screwed to the top of the tube and holds the assembly in place. The clamp 27 has a flared aperture at the top so as not to obstruct the X-rays between their focus on the anticathode towards the -spec trom-eters.

The stage according to the invention offers a considerable number of advantages for Castaing microprobe analysis.

Its Large :efiective width permits the mounting of samples enclosed in pellets of a diameter of 25.4 mm. or solid samples of the same dimensions.

The system for drawing the stage along the dovetail slide guide is operable from outside without interrupting analysis and multiplies by approximately 15 the analysable surface of the sample itself (in relation to the capacity of the original system), while leaving sufficient room for the controls.

Moreover, as a result of the steps according to the invention, the problem of the controlsboth as regards their surface condition and their geometric position is greatly facilitated. 'The controls are now enclosed in the same block as the sample or in separate blocks. They'can thus be prepared, polished, metallised or repolished without any danger of fracture and with their surface always in the focussing plane.

Finally, some examples of practical use of the stage according to the invention willbe given below:

(1) The mounting of a 25.4 mm. diameter pellet enclosing one or more special samples and controls (for example radioactive) and two parallelepipedic blocks enclosing large series of conventional controls (see Fig.

(2) The mounting of two 25.4 mm. diameter pellets enclosing a series of special samples and controls (see FIG.

(3) Various mountings of large samples which may or may not be enclosed with their controls, or a large sample :and a small block of appropriate controls (see FIGS. 6d, 6e);

(4) The mounting of six thin sections for microradiography or microd-itfraction or microanaylsis, and a plurality of parallelepipedic blocks enclosing solid controls and samples;

(5) The mounting of an enclosed radioactive sample with a control block and a lead ra-diobiological screen (see PEG. 6e).

1 claim:

1. A multi-purpose stage for electronic probe microanalysis comprising a frame, slide guides under said frame, two pluralities of vertical apertures in the frame, a first plurality of apertures lateraly located in the frame at distances between 15 and 19 mm., and adapted to receive a number of securing elements, the securing elements being positioned to receive, their locations, test-pieces to be examined, a second plurality of apertures centrally located and adapted to receive thin section holders, the axial distances between the apertures of each plurality of apertures being substantially 7 mm., and the diameter of the first and second plur-alities of apertures being substantially and respectively 2 and 6 mm, an operating slide guide, an operating rod fixed to the operating slide guide for displacement of the frame along the slide guides.

2. A stage according to claim 1 wherein thin section holders comprise a tube, a first support diaphragm, a thin sect-ion to be radiographed, a spacer ring, a second diaphragm, ran anticathode thin section and a flared anticathod-e clamp superposed one over the other.

3. A stage according to claim 1 wherein the securing elements comprise a leg forming a tubular strut and a conical washer mounted on the leg, the bottom plane surface of the washer being applied against the top surface of the test-pieces or pellets.

4. A stage according to claim 1 wherein the second plurality of apertures are aligned on the central axis, and the first plurality of apertures are adjacent to the first plurality of apertures.

References Cited by the Examiner UNITED STATES PATENTS 2,423,158 7/47 Rung-e 25049.5 2,849,619 8/58 Eisfeldt 250-495 RALPH G. NILSON, Primary Examiner. 

1. A MULTI-PURPOSE STAGE FOR ELECTRONIC PROBE MICROANALYSIS COMPRISING A FRAME, SLIDE GUIDES UNDER SAID FRAME, TWO PLURALITIES OF VERTICAL APERTURES IN THE FRAME, A FIRST PLURALITY OF APERTURES LATERALY LOCATED IN THE FRAME AT DISTANCES BETWEEN 15 AND 19MM., AND ADAPTED TO RECEIVE A NUMBER OF SECURING ELEMENTS, THE SECURING ELEMENTS BEING POSITIONED TO RECEIVE, WITHIN THEIR LOCATIONS, TEST-PIECES TO BE EXAMINED, A SECOND PLURALITY OF APERTURES CENTRALLY LOCATED AND ADAPTED TO RECEIVE THIN SEC- 